The present embodiments relate to contrast agent imaging. In particular, timing of scan acquisition is provided for medical diagnostic contrast agent imaging.
Contrast agents are used in various types of medical diagnostic imaging. For ultrasound, the contrast agents are microspheres that reflect acoustic energy. The flow of contrast agents into a region (inflow or wash-in) and out of the region (outflow or wash-out) may be monitored with ultrasound scanning. The inflow and outflow may assist in diagnosis of problems in the circulatory system of the patient. Perfusion of contrast agents may be used to assist diagnosis of organs of the patient. Ultrasound scanning occurs sufficiently rapidly compared to the flow of the contrast agents to allow monitoring of the inflow and outflow. However, the microspheres may collapse due to the acoustic energy used for scanning, and ultrasound imaging may have relatively poor signal-to-noise ratio as compared to other types of scanning.
For magnetic resonance (MR) imaging, the contrast agents are gadolinium-based materials. MR scanning may occur relatively slowly as compared to the flow of contrast agents. A given scan for MR imaging takes sufficiently long relative to the movement of contrast agents that tracking inflow or outflow may be unreliable in some situations. The MR scan process may extend over a period in which different concentrations of contrast agent occur within a region, providing poor temporal resolution.
For computed tomography (CT) imaging, the contrast agents are iodine-based materials. CT scans may be performed relatively rapidly compared to the rate of flow. To monitor the flow, multiple CT scans are performed so that the inflow and/or outflow are not missed. However, scanning multiple times with CT results in increased radiation dose. This may be a concern particularly where scans are performed before contrast agents even arrive at and/or after leaving the scan region in order to not miss the arrival or outflow.